Magneto-hydrodynamic generators



March 11, 1969 JEAN-Lows CHEVALLEY 3,432,692

MAGNETO-HYDRODYNAMIC GENERATORS Filed Aug. 19, 1966 B j lll 3 /a 25 29 f 5. /50 ,9

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United States Patent() 3,432,692 MAGNETO-HYDRODYNAMIC GENERATORS Jean-Louis Chevalley, Carouge, Geneva, Switzerland,

assignor to Eric Brocher, Cheuebougerie, Geneva, Switzerland Filed Aug. 19, 1966, Ser. No. 573,662 Claims priority, application Switzerland, Aug. 26, 1965, 12,015/ 65 U.S. Cl. 310-11 4 Claims Int. Cl. H02k 45 00 ABSTRACT OF THE DISCLOSURE A 4magneto-hydrodynamic generator comprising at least one pair of shock tubes is provided, there being a reservoir of working fluid communicating with each tube at one end, a source of heated and compressed auxiliary tluid connected to the other end of the tubes via a cyclical- 1y controlled distributor, at least one pair of parallel electrodes arranged within each tube on oppositely arranged wall portions of its inner surface, adjacent the end communicating with the reservoir of working uid, and means producing in each tube a transverse magnetic lield parallel to said electrodes. The distributor is adapted to introduce the auxiliary fluid alternately into the tubes of the pair and to discharge said uid after a predetermined lapse of time. The electrodes are connected to output terminals so as to obtain an alternating voltage whose period is formed by two alternations each produced by one tube of the pair.

The present invention relates to a magneto-hydrodynamic generator.

As is known, the efficiency of a magneto-hydrodynamic generator depends on the conductivity of its work fluid, which conductivity depends in particular on temperature.

The method and apparatus disclosed in copending appli- A cation Ser. No. 359,874 of Eric Brocher and Walter Dallenbach, led Apr. l5, 1964, and on which Patent No. 3,350,584 since has issued, have the great advantage of enabling the use of an economic source of heat to heat a compressed auxiliary uid and the Work fluid of the generator, and of raising the temperature of the lwork fluid, through shock wave compression, to a working temperature which is substantially greater than that of conventional heat sources.

This, however, involves the use of cyclically controlled distributors to control the introduction and discharge of the uids so as to produce shock wave compressions in order to yield trains of ionised work fluid pulses. Clearly, the production of alternating electric energy by means of these pulse trains will thus necessitate distributors whose opening cycle is repeated at -a frequency corresponding to that of the alternating current being produced. Multi-way rotary distributors are well suited for this purpose. As is known, movable mechanical elements are far more liable to damage caused by high temperature than stationary elements.

An object of the present invention is to provide a magneto-hydrodynamic generator capable of operating at temperatures far exceeding those of conventional heat sources, in which the number of movable mechanical elements that are exposed to such temperatures is reduced to a minimum.

The generator according to the present invention is intended to enable constant load operation at temperatures of about or greater than 3000o C., and comprises at least one pair of shock tubes each communicating at one of its ends with a reservoir adapted to contain the work iluid of said generator, a source of heated and compessed auxiliary uid connected to the other end of said tubes via a cycli- "lee cally controlled distributor, said distributor being adapted to introduce the auxiliary tluid alternately into the tubes of said pair and to discharge said Huid after a predetermined lapse of time, each of said tubes being provided, near the end thereof connected to the work lluid reservoir, with at least two parallel electrodes so disposed as to form two opposite faces of its inner wall and with means for producing a magnetic eld parallel to the electrodes and transverse to the tube, the electrodes of said one pair of tubes being connected to the output terminals of the generator so as to obtain thereat an alternating voltage whose period is formed by two alternations which are each produced by one tube of said one pair.

In the accompanying drawings:

FIGURE l is a schematic representation of an embodiment of the invention generator operating in a closed cycle; and

FIGURE 2 shows, by means of an entropy diagram indicating absolute temperature T and pressure p as a function of entropy S, the thermodynamic cycles of the work tluid and of the auxiliary fluid in the generator of FIGURE l.

The generator shown in FIGURE l comprises a pair of parallel shock tubes 1 and 2 connected at one end by ditfusers 3 and 4 to reservoirs 5 and 6 each containing an equal amount of work fluid. The temperature and pressure of this uid may have any suitable initial value. At the other end of tubes 1 and 2, i.e., at their input, a rotary distributor 7 is provided for alternately and cyclically connecting these tubes with one of a pair of conduits 8 and 9 for introducing a heated and compressed auxiliary uid and with one of a pair of conduits 10 and 11 for discharging the expanded auxiliary fluid.

The distributor 7 consists here of a disc which is disposed symmetrically opposite the inlets of tubes 1 and 2 and Vwhich cooperates with drive means (not shown) for rotating it at a predetermined speed about an axis which is contained in a plane common to the axes of tubes 1 and 2 and parallel thereto. The disc 7 is formed with two passages 12 and 13, passage 12 serving to establish communication successively between tube 1 and conduit 8 and bewteen tube 2 and passage 9 and passage serving to establish communication successively between tube 2 land conduit 11 and between tube 1 and conduit 10 for the introduction and discharge of the auxiliary tluid. In the position illustrated in this figure, passage 12 lies between the inlet cond-uit 8 and tube 1 to enable the intlow of compressed and heated auxiliary fluid into the latter. At the same time passage 13 lies between the outlet conduit 11 and tube 2 to enable the outow of expanded auxiliary fluid from the latter. When the distributor has rotd through in relation to the position illustrated in FIGURE 1, tube 2 will communicate via passage 12 with inlet conduit 9 and tube 1 will communicate via passage 13 with discharge conduit 10. The disc 7 thus performs a cyclic operation which comprises for each tube the following phascsclosure, introduction of auxiliary gas, closure, and discharge of auxiliary gas. The duration of the yauxiliary gas introduction and discharge phases will of course depend on the peripheral width of the crosssections of passages 12 and 13 and on the rotational speed of the disc 7. It would thus be of advantage to provide means (not shown) for accurately adjusting said duration, for example means for varying the peripheral limits of said cross-sections, in order that the closure and throughflow phases can be adjusted to the various working conditions that are envisaged. Moreover, the rotational speed of the disc 7 is so chosen, for reasons given below, that it may carry out one revolution per cycle of the alternating current to be produced by the generator.

The tubes 1 and 2 are each provided, near the diffusers 3 and 4, with two electrodes, respectively identified by numerals 14, and 16, 17, which are disposed opposite one another and parallel to the tube axis. The electrodes 14, 15 and 16, 17 are mounted so as to be electrically insulated from the associated tube and so as to have their inner surfaces washed by the fluid flowing through this tube. Electrodes 14 and 17 are connected by leads 14a and 17a to the output terminal 18 of the generator and electrodes 15 and 16 are connected by leads 15a and 16a t0 the other output terminal 19 of the generator.

The tubes are further provided with electro-magnets whose windings 20 and 21 serve to produce magnetic fields B1 and B2 each of which is transverse to the axis of the associated tube and passes between the electrodes. The electro-magnets are so arranged that the two fields may be parallel--in the present instance at right angles to the plane of the drawing-and extend over the entire length of the electrodes.

The generator illustrated in FIGURE 1 comprises moreover two compressors 22 and 23, with an intermediate cooler 24, and a heat generator 25 for heating the compressed auxiliary fluid to a temperature of 1000 to 2000 C. A conduit 26 conveys the compressed auxiliary fluid from the compressor 23 to a recuperator 27 whence it is conveyed by a conduit 28 to the heat generator 25. The heated and compressed auxiliary fluid then flows through conduit 29 into input conduits 8 and 9 and is alternately introduced, by the rotary disc 7, as described above, into tubes 1 and 2. The discharge conduits 10 and 11, respectively associated with 'tubes 1 land 2, open into a recycling conduit 30 leading to the inlet of an expansion turbine 31 driving compressors 22 and 23. An electric motor 32 which, in the present instance, is supplied by the generator, serves to lprovide the additional energy required to drive these compressors. The auxiliary fluid flows from the turbine 31, via a conduit 33, the recuperator 27 and Y a cooler 34, into the suction conduit of compressor 22. The thermodynamic cycles carried out by the two flulds during operation of the above described generator are schematically represented in the entropy diagram of FIG- URE 2.

The auxiliary fluid cycle comprises the following stages:

A-Al: rst compression in compressor 22. A1-B1z intermediate cooling in cooler 24. Bl-B: second compression in compressor 23. B-F: preheating in recuperator 27.

F-C: heating in heat generator 25.

C-D1: first expansion in shock tubes 1 and 2. Dl-D: second expansion in turbine 31. D-E: first cooling in recuperator 27.

E-A: second cooling in exchanger 34.

The work fluid cycle comprises the following stages:

I-II: compression (and superheating) by shock wave in tubes 1 and 2.

II-III: expansion by ilowing between the generator electrodes 14, 15 and 16, 17.

III-I: cooling due to heat losses through the walls of shock tubes 1 and 2.

It should be noted that the cycles represented in FIGURE 2 are theoretical cycles and do not take into account the efliciencies of the compressors, of the turbine and of the exchangers. It will be observed that the temperature of the work fluid at point I is greater than that of the heat source 25, i.e. than that of the auxiliary fluid at point C. This is due to the fact that cycle I, II, III shown in FIG- URE 2 is that carried out under constant load conditions of the generator.

When starting the generator, the work fluid contained in reservoirs 5 and 6 and in tubes 1 and 2, whose inlets are closed off by the disc 7, can either be preheated by an external source, possibly indirectly by the heat generator 25, or have any temperature, even ambient temperature. In the latter instance, the generator can be started under no load conditions in order to subject the fluid to a succession of compressions each followed by expansion so that it may gradually be heated up by the losses due to the irreversible nature of these two operations. Once the work fluid has reached the desired preheating temperature, the generator is loaded and the iluid begins to carry out working cycles with its temperature increasing at each cycle, until reaching a point at which this cyclic operation stabilizes itself under constant lead conditions as shown by points I, II, III in FIGURE 2. The stabilization level of this cyclic operation will depend on the cooling effect (III-I) that is obtained on the walls of the shock tubes. Although it is advantageous to carry out the work cycle at temperature levels which are as high as possible in order to improve the efciency and the `specific power of the generator, the problem of the resistance of materials to high temperature will require in certain cases the use of additional means for cooling the shock tubes in order that they may withstand very high temperatures better and in order to stabilize the work fluid cycle under constant load conditions at a temperature level which is very close to the limit imposed bythe refractory materials being used.

I claim:

1. A magneto-hydrodynamic generator which comprises at least one pair of shock tubes each communicating at one of its ends with a reservoir adapted to contain the work fluid of said generator, a source of heated and compressed auxiliary -fluid connected to the other end of said tubes via a cyclically controlled distributor, said distributor being adapted to introduce the auxiliary fluid alternately into the tubes of said pair and to discharge said fluid after a predetermined lapse of time, each of said tubes being provided, near the end thereof connected to the work fluid reservoir, with at least two parallel electrodes so disposed as to form two opposite faces of its inner wall and with means for producing .a magnetic field parallel to the electrodes and transverse to the tube, the electrodes of said one pair of tubes being connected to the output terminals of the generator so as to obtain thereat an alternating voltage whose period is formed by two alternations which are each produced by one tube of said one pair.

2. A generator according to claim 1 wherein said distributor includes a rotary closure member comprising two passages which successively and cyclically connect one of the tubes of said one pair to an auxiliary fluid input conduit and the other tube of said one pair to a discharge conduit for said fluid.

3. A lgenerator according to claim 1, further comprising means for regulating the introduction and discharge time for the auxiliary fluid through said distributor.

4. A generator according to claim 1, further comprising a recycling conduit for collecting the auxiliary fluid discharged from said tubes and for returning it to said source.

References Cited UNITED STATES PATENTS 3,161,789 12/1964 Nagamatsu et al 310--11 DAVID X. SLINEY, Primary Examiner. 

